U.S. patent number 11,387,110 [Application Number 16/642,636] was granted by the patent office on 2022-07-12 for plasma processing apparatus and plasma processing method.
This patent grant is currently assigned to HITACHI HIGH-TECH CORPORATION. The grantee listed for this patent is HITACHI HIGH-TECH CORPORATION. Invention is credited to Yasushi Sonoda.
United States Patent |
11,387,110 |
Sonoda |
July 12, 2022 |
Plasma processing apparatus and plasma processing method
Abstract
A plasma processing apparatus, including a processing; a first
radio frequency power source; a sample stage on which the sample is
placed; a second radio frequency power; and a control device
configured to control, when the second radio frequency power source
is controlled based on a change in a plasma impedance, which is
generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the second radio frequency power is changed from a value of the
second radio frequency power in the first step to a value of the
second radio frequency power in the second step, and a supply time
of the first gas such that a supply time of the second radio
frequency power in the first step is substantially equal to a time
of the first step.
Inventors: |
Sonoda; Yasushi (Tokyo,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI HIGH-TECH CORPORATION |
Tokyo |
N/A |
JP |
|
|
Assignee: |
HITACHI HIGH-TECH CORPORATION
(Tokyo, JP)
|
Family
ID: |
1000006428518 |
Appl.
No.: |
16/642,636 |
Filed: |
June 20, 2019 |
PCT
Filed: |
June 20, 2019 |
PCT No.: |
PCT/JP2019/024437 |
371(c)(1),(2),(4) Date: |
February 27, 2020 |
PCT
Pub. No.: |
WO2020/012907 |
PCT
Pub. Date: |
January 16, 2020 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200402809 A1 |
Dec 24, 2020 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
21/30655 (20130101); H01J 37/321 (20130101); H01J
37/32009 (20130101); H01J 37/32715 (20130101); H01J
37/32174 (20130101); H01L 21/67069 (20130101); H01J
2237/3343 (20130101) |
Current International
Class: |
H01L
21/30 (20060101); H01L 21/67 (20060101); H01L
21/3065 (20060101); H01J 37/32 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
S60050923 |
|
Mar 1985 |
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JP |
|
H02105413 |
|
Apr 1990 |
|
JP |
|
2009521594 |
|
Jun 2009 |
|
JP |
|
2016092342 |
|
May 2016 |
|
JP |
|
2017174537 |
|
Sep 2017 |
|
JP |
|
20090082493 |
|
Jul 2009 |
|
KR |
|
2007061633 |
|
May 2007 |
|
WO |
|
2008061069 |
|
May 2008 |
|
WO |
|
Other References
Office Action dated Jan. 20, 2016 for corresponding Korean
Application No. 10-2015-0016544. cited by applicant .
International Search Report w/Tranlsation dated Aug. 27, 2019,
issued in PCT/JP2019/024437. cited by applicant.
|
Primary Examiner: Tan; Vibol
Attorney, Agent or Firm: Miles & Stockbridge, P.C.
Claims
The invention claimed is:
1. A plasma processing apparatus, comprising: a processing chamber
in which a sample is subjected to plasma processing; a first radio
frequency power source configured to supply a first radio frequency
power for generating a plasma; a sample stage on which the sample
is placed; a second radio frequency power source configured to
supply a second radio frequency power to the sample stage; and a
control device configured to control, when the first radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the first radio frequency power is changed from a
value of the first radio frequency power in the first step to a
value of the first radio frequency power in the second step, a
supply time of the first gas by using a first time and a second
time such that a supply time of the first radio frequency power in
the first step is substantially equal to a time of the first step,
wherein the first step and the second step are steps of plasma
processing conditions, the first time is a time period from a start
time of the first step to a start time of a supply of the first
gas, and the second time is a time period from a finish time of the
first step to a finish time of the supply of the first gas.
2. A plasma processing apparatus, comprising: a processing chamber
in which a sample is subjected to plasma processing; a first radio
frequency power source configured to supply a first radio frequency
power for generating a plasma; a sample stage on which the sample
is placed; a second radio frequency power source configured to
supply a second radio frequency power to the sample stage; and a
control device configured to control, when the second radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the second radio frequency power is changed from a
value of the second radio frequency power in the first step to a
value of the second radio frequency power in the second step, a
supply time of the first gas by using a first time and a second
time such that a supply time of the second radio frequency power in
the first step is substantially equal to a time of the first step,
wherein the first step and the second step are steps of plasma
processing conditions, the first time is a time period from a start
time of the first step to a start time of a supply of the first
gas, and the second time is a time period from a finish time of the
first step to a finish time of the supply of the first gas.
3. The plasma processing apparatus according to claim 1, wherein
the control device controls the supply time of the first gas such
that the supply time of the first gas is a time obtained by
subtracting a predetermined value from the time of the first step,
and the predetermined value is a value obtained by subtracting the
first time from the second time.
4. A plasma processing apparatus, comprising: a processing chamber
in which a sample is subjected to plasma processing; a first radio
frequency power source configured to supply a first radio frequency
power for generating a plasma; a sample stage on which the sample
is placed; a second radio frequency power source configured to
supply a second radio frequency power to the sample stage; and a
control device configured to control, when the first radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the first radio frequency power is changed from a
value of the first radio frequency power in the first step to a
value of the first radio frequency power in the second step, a
supply time of the second gas by using a first time and a second
time such that a supply time of the first radio frequency power in
the second step is substantially equal to a time of the second
step, wherein the first step and the second step are steps of
plasma processing conditions, the first time is a time period from
a start time of the first step to a start time of a supply of the
first gas, and the second time is a time period from a finish time
of the first step to a finish time of the supply of the first
gas.
5. A plasma processing apparatus, comprising: a processing chamber
in which a sample is subjected to plasma processing; a first radio
frequency power source configured to supply a first radio frequency
power for generating a plasma; a sample stage on which the sample
is placed; a second radio frequency power source configured to
supply a second radio frequency power to the sample stage; and a
control device configured to control, when the second radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the second radio frequency power is changed from a
value of the second radio frequency power in the first step to a
value of the second radio frequency power in the second step, a
supply time of the second gas by using a first time and a second
time such that a supply time of the second radio frequency power in
the second step is substantially equal to a time of the second
step, wherein the first step and the second step are steps of
plasma processing conditions, the first time is a time period from
a start time of the first step to a start time of a supply of the
first gas, and the second time is a time period from a finish time
of the first step to a finish time of the supply of the first
gas.
6. The plasma processing apparatus according to claim 4, wherein
the control device controls the supply time of the second gas such
that the supply time of the second gas is a time obtained by
subtracting a predetermined value from the time of the second step,
and the predetermined value is a value obtained by subtracting the
second time from the first time.
7. A plasma processing method in which a plasma processing
apparatus is used, the plasma processing apparatus including: a
processing chamber in which a sample is subjected to plasma
processing; a first radio frequency power source configured to
supply a first radio frequency power for generating a plasma; a
sample stage on which the sample is placed; and a second radio
frequency power source configured to supply a second radio
frequency power to the sample stage, the plasma processing method
comprising: controlling, when the first radio frequency power
source is controlled based on a change in a plasma impedance, which
is generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the first radio frequency power is changed from a value of the
first radio frequency power in the first step to a value of the
first radio frequency power in the second step, a supply time of
the first gas by using a first time and a second time such that a
supply time of the first radio frequency power in the first step is
substantially equal to a time of the first step, wherein the first
step and the second step are steps of plasma processing conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and the second time
is a time period from a finish time of the first step to a finish
time of the supply of the first gas.
8. A plasma processing method in which a plasma processing
apparatus is used, the plasma processing apparatus including: a
processing chamber in which a sample is subjected to plasma
processing; a first radio frequency power source configured to
supply a first radio frequency power for generating a plasma; a
sample stage on which the sample is placed; and a second radio
frequency power source configured to supply a second radio
frequency power to the sample stage, the plasma processing method
comprising: controlling, when the second radio frequency power
source is controlled based on a change in a plasma impedance, which
is generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the second radio frequency power is changed from a value of the
second radio frequency power in the first step to a value of the
second radio frequency power in the second step, a supply time of
the first gas by using a first time and a second time such that a
supply time of the second radio frequency power in the first step
is substantially equal to a time of the first step, wherein the
first step and the second step are steps of plasma processing
conditions, the first time is a time period from a start time of
the first step to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
9. A plasma processing method in which a plasma processing
apparatus is used, the plasma processing apparatus including: a
processing chamber in which a sample is subjected to plasma
processing; a first radio frequency power source configured to
supply a first radio frequency power for generating a plasma; a
sample stage on which the sample is placed; and a second radio
frequency power source configured to supply a second radio
frequency power to the sample stage, the plasma processing method
comprising: controlling, when the first radio frequency power
source is controlled based on a change in a plasma impedance, which
is generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the first radio frequency power is changed from a value of the
first radio frequency power in the first step to a value of the
first radio frequency power in the second step, a supply time of
the second gas by using a first time and a second time such that a
supply time of the first radio frequency power in the second step
is substantially equal to a time of the second step, wherein the
first step and the second step are steps of plasma processing
conditions, the first time is a time period from a start time of
the first step to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
10. A plasma processing method in which a plasma processing
apparatus is used, the plasma processing apparatus including: a
processing chamber in which a sample is subjected to plasma
processing; a first radio frequency power source configured to
supply a first radio frequency power for generating a plasma; a
sample stage on which the sample is placed; and a second radio
frequency power source configured to supply a second radio
frequency power to the sample stage, the plasma processing method
comprising: controlling, when the second radio frequency power
source is controlled based on a change in a plasma impedance, which
is generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the second radio frequency power is changed from a value of the
second radio frequency power in the first step to a value of the
second radio frequency power in the second step, a supply time of
the second gas by using a first time and a second time such that a
supply time of the second radio frequency power in the second step
is substantially equal to a time of the second step, wherein the
first step and the second step are steps of plasma processing
conditions, the first time is a time period from a start time of
the first step to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
11. The plasma processing apparatus according to claim 2, wherein
the control device controls the supply time of the first gas such
that the supply time of the first gas is a time obtained by
subtracting a predetermined value from the time of the first step,
and the predetermined value is a value obtained by subtracting the
first time from the second time.
12. The plasma processing apparatus according to claim 5, wherein
the control device controls the supply time of the second gas such
that the supply time of the second gas is a time obtained by
subtracting a predetermined value from the time of the second step,
and the predetermined value is a value obtained by subtracting the
second time from the first time.
Description
TECHNICAL FIELD
The present invention relates to a plasma processing apparatus and
a plasma processing method.
BACKGROUND ART
In a manufacturing process of a semiconductor device, there is a
demand for miniaturization and integration of components included
in the semiconductor device. For example, in an integrated circuit
and a nanoelectronic mechanical system, a nanoscale structure is
further promoted.
In the manufacturing process of the semiconductor device, a
lithography technique is usually used to forma fine pattern. In
this technique, a pattern of a device structure is applied on a
resist layer, and a substrate exposed by the pattern on the resist
layer is selectively etched and removed. In subsequent treatment
processes, if another material is deposited in an etching region,
the integrated circuit can be formed.
Incidentally, in an etching process of transferring a mask shape on
a lower layer film, relatively higher shape controllability is
required. For example, when etching a vertical shape having a high
aspect ratio, an advanced technique is required. As one of such
techniques, a gas pulse method for performing a plasma etching
treatment is known, in which an etching gas and a deposition gas
that forms a protective film having a high etching resistance
against the etching gas are periodically and alternately introduced
into a processing chamber while a plasma is generated.
For example, PTL 1 discloses that when the gases are alternately
introduced, in order to enhance effect of each gas, a radio
frequency power supplied to a sample stage is changed in
synchronization with the introduction of the gas, such that a
self-bias is generated in a process of introducing the etching gas
and a process of introducing the deposition gas.
When an etching treatment is performed while alternately performing
etching and forming the protective film by using the gas pulse
method, a minute step shape referred to as scalloping is formed on
a side surface of a processed hole after the etching, but this
minute step shape is undesirable when forming the semiconductor
device. In order to prevent this minute step shape, it is effective
to shorten an introduction time of the gases to be alternately
introduced to one to three seconds.
An amount of the gases introduced into the processing chamber is
generally controlled by giving a control signal for introducing a
desired gas flow rate to a gas supply device, such as a mass flow
controller (MFC). However, during a time period from a time when
the flow rate signal is given to the gas supply device to a time
when the gas is introduced into the processing chamber, a delay
about 1 second is generated by influences such as a response time
of the gas supply device, or pressure and a gas flow in the
processing chamber, gas pipes and a shower plate. Further, the
delay has a variation of about 0.2 to 0.3 seconds.
Therefore, when a gas introduction time is about 1 to 3 seconds, it
is necessary to perform control in consideration of a delay that is
from when the control signal is given to the gas supply device to
when the gas is actually introduced into the processing chamber.
This is because if such control is not performed, a time gap that
cannot be ignored is generated between a timing of introducing the
gas of a process for etching or forming the protective film in the
processing chamber and a timing of controlling process parameters
such as a bias and a power for generating the plasma to values
suitable for each process, so that optimal treatment will not be
implemented.
In addition, in order to reduce the influence of variations in the
delay time of gas introduction, it is necessary to control other
process parameters while grasping an accurate time of introducing
the gas into the processing chamber in real time.
A method for determining exchange of the etching gas and the
deposition gas is disclosed in PTL 2, in which by detecting a gas
ratio using an emission spectrum and a mass spectrometer, a
switching time between the introduction of the etching gas and the
deposition gas is obtained and the radio frequency power is
synchronized.
In addition, a method as described in PTL 3 is known, in which
after detecting a switch from one gas to the other gas based on a
change in plasma impedance, the radio frequency power source is
controlled to change the radio frequency power supplied from the
radio frequency power source.
CITATION LIST
Patent Literature
PTL 1: JP-A-S60-50923 PTL 2: JP-A-H2-105413 PTL 3:
JP-A-2016-92342
SUMMARY OF INVENTION
Technical Problem
However, in the related art, a problem of machine differences that
occur between a plurality of plasma processing apparatuses is not
been sufficiently considered. Specifically, in the methods
disclosed in PTL 2 and PTL 3, since the radio frequency power is
changed based on the switching of introduction of the gases, a time
during which the etching gas or the deposition gas, or the like
flows in the processing chamber becomes a time during which the
radio frequency power corresponding to each gas is applied.
A gas supply system configured with the gas supply device and the
like is less responsive than the radio frequency power source, and
as a result, a difference in responsiveness between the gas supply
systems of a plurality of devices is also larger than a difference
in responsiveness between the radio frequency power sources of the
plurality of devices. However, since an applying time of the radio
frequency power is determined by the time during which the gas
flows through the processing chamber, a machine difference in the
responsiveness of the gas supply systems appears as a machine
difference in the applying time of the radio frequency power
between the plurality of plasma processing apparatuses. As a
result, there is a problem that a machine difference larger than a
machine difference in the applying time that has occurred due to
the machine difference in responsiveness of the radio frequency
power source occurs between the plasma processing apparatuses, and
the treatment time varies and mass production stability is
reduced.
As described above, in view of the above problems, an object of the
invention is to provide a plasma processing apparatus and a plasma
processing method with which plasma etching can be performed with
high shape controllability and a small machine difference in the
applying time of radio frequency power among a plurality of plasma
processing apparatuses that perform plasma processing while
periodically switching gases.
Solution to Problem
In order to solve above problems, a representative plasma
processing apparatus according to the invention is provided. The
plasma processing apparatus includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed;
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage; and
a control device configured to control, when the first radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the first radio frequency power is changed from a
value of the first radio frequency power in the first step to a
value of the first radio frequency power in the second step, a
supply time of the first gas by using a first time and a second
time such that a supply time of the first radio frequency power in
the first step is substantially equal to a time of the first step,
in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing apparatus according to
the invention is provided. The plasma processing apparatus
includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed;
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage; and
a control device configured to control, when the second radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the second radio frequency power is changed from a
value of the second radio frequency power in the first step to a
value of the second radio frequency power in the second step, a
supply time of the first gas by using a first time and a second
time such that a supply time of the second radio frequency power in
the first step is substantially equal to a time of the first step,
in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing apparatus according to
the invention is provided. The plasma processing apparatus
includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed;
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage; and
a control device configured to control, when the first radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the first radio frequency power is changed from a
value of the first radio frequency power in the first step to a
value of the first radio frequency power in the second step, a
supply time of the second gas by using a first time and a second
time such that a supply time of the first radio frequency power in
the second step is substantially equal to a time of the second
step, in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing apparatus according to
the invention is provided. The plasma processing apparatus
includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed;
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage; and
a control device configured to control, when the second radio
frequency power source is controlled based on a change in a plasma
impedance, which is generated when a first gas that is a gas for a
first step is switched to a second gas that is a gas for a second
step, such that the second radio frequency power is changed from a
value of the second radio frequency power in the first step to a
value of the second radio frequency power in the second step, a
supply time of the second gas by using a first time and a second
time such that a supply time of the second radio frequency power in
the second step is substantially equal to a time of the second
step, in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing method in which a
plasma processing apparatus is used according to the invention is
provided.
The plasma processing apparatus includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed; and
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage.
The plasma processing method includes:
controlling, when the first radio frequency power source is
controlled based on a change in a plasma impedance, which is
generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the first radio frequency power is changed from a value of the
first radio frequency power in the first step to a value of the
first radio frequency power in the second step, a supply time of
the first gas by using a first time and a second time such that a
supply time of the first radio frequency power in the first step is
substantially equal to a time of the first step, in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing method in which a
plasma processing apparatus is used according to the invention is
provided.
The plasma processing apparatus includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed; and
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage.
The plasma processing method includes:
controlling, when the second radio frequency power source is
controlled based on a change in a plasma impedance, which is
generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the second radio frequency power is changed from a value of the
second radio frequency power in the first step to a value of the
second radio frequency power in the second step, a supply time of
the first gas by using a first time and a second time such that a
supply time of the second radio frequency power in the first step
is substantially equal to a time of the first step, in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing method in which a
plasma processing apparatus is used according to the invention is
provided.
The plasma processing apparatus includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed; and
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage.
The plasma processing method includes:
controlling, when the first radio frequency power source is
controlled based on a change in a plasma impedance, which is
generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the first radio frequency power is changed from a value of the
first radio frequency power in the first step to a value of the
first radio frequency power in the second step, a supply time of
the second gas by using a first time and a second time such that a
supply time of the first radio frequency power in the second step
is substantially equal to a time of the second step, in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Further, a representative plasma processing method in which a
plasma processing apparatus is used according to the invention is
provided.
The plasma processing apparatus includes:
a processing chamber in which a sample is subjected to plasma
processing;
a first radio frequency power source configured to supply a first
radio frequency power for generating a plasma;
a sample stage on which the sample is placed; and
a second radio frequency power source configured to supply a second
radio frequency power to the sample stage.
The plasma processing method includes:
controlling, when the second radio frequency power source is
controlled based on a change in a plasma impedance, which is
generated when a first gas that is a gas for a first step is
switched to a second gas that is a gas for a second step, such that
the second radio frequency power is changed from a value of the
second radio frequency power in the first step to a value of the
second radio frequency power in the second step, a supply time of
the second gas by using a first time and a second time such that a
supply time of the second radio frequency power in the second step
is substantially equal to a time of the second step, in which
the first step and the second step are steps of plasma processing
conditions,
the first time is a time period from a start time of the first step
to a start time of a supply of the first gas, and
the second time is a time period from a finish time of the first
step to a finish time of the supply of the first gas.
Advantageous Effect
According to the invention, the plasma processing apparatus and the
plasma processing method with which the plasma etching can be
performed with high shape controllability and a small machine
difference in the applying time of radio frequency power among a
plurality of plasma processing apparatuses that perform plasma
processing while periodically switching gases.
Problems, configurations, and effects other than those described
above will be clarified by the following description of
embodiments.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a longitudinal sectional view illustrating a
configuration of a plasma processing apparatus according to an
embodiment of the invention.
FIG. 2 is a diagram illustrating that a radio frequency applying
time fluctuates when a radio frequency power is changed in
synchronization with gas switching.
FIG. 3 is a flowchart illustrating operations in which a setting
time of a gas supply setting signal transmitted to a gas supply
device according to the embodiment of the invention is changed
based on a delay time from when a supply is set to when a gas is
introduced into a processing chamber.
FIG. 4 is a timing chart when the setting time of the gas supply
setting signal transmitted to the gas supply device is adjusted
according to the flowchart of FIG. 3.
DESCRIPTION OF EMBODIMENTS
Hereinafter, an embodiment of the invention is described with
reference to the drawings. FIG. 1 is a longitudinal sectional view
illustrating an outline of an overall configuration of a plasma
processing apparatus according to the present embodiment of the
invention. A shower plate 102 for introducing an etching gas into a
vacuum vessel 101 and a dielectric window 103 for air tightly
sealing an upper portion of a processing chamber are disposed on an
upper portion of the vacuum vessel 101 to constitute a processing
chamber 104. A plurality of gas supply devices (MFC) 106 are
connected to the shower plate 102 via a gas pipe 105, and each gas
supply device 106 is respectively connected to a source (not
illustrated) of a treatment gas, such as SF.sub.6 gas, O.sub.2 gas,
or the like, for performing a plasma etching treatment.
A first process gas (etching gas) for performing an etching
treatment with the plurality of gas supply devices and a second
process gas (deposition gas) for performing a protective film
forming treatment can be alternately introduced into the processing
chamber 104 via the gas pipe 105 and the shower plate 102 at a
constant cycle. Here, the first process gas constitutes a first
step gas, that is, a first gas, and the second process gas
constitutes a second step gas, that is, a second gas.
The etching gas and the deposition gas may be a single gas or a
combination of a plurality of gases. In order to reduce discharge
instability during gas switching, it is desirable to add a rare gas
that does not significantly change characteristics of each process,
such as Ar gas and He gas, into the etching gas and deposition gas
as a common gas. Further, it is assumed that a vacuum exhaust
device (not illustrated) is connected to the vacuum vessel 101 via
a vacuum exhaust port 115, such that pressure in the processing
chamber 104 can be controlled.
A plasma generation mechanism in this plasma processing apparatus
is configured with an electromagnetic wave generation power source
(magnetron) 107 that generates 2.45 GHz electromagnetic waves
referred to as microwaves, a microwave matching unit 108 and a
magnetic field generation coil 109. The plasma generation mechanism
generates plasma in the processing chamber 104 by an electron
cyclotron resonance (ECR) between an electromagnetic wave (first
radio frequency power) oscillated from the electromagnetic wave
generation power source 107 which is a first radio frequency power
source and a magnetic field formed by the magnetic field generation
coil 109.
In addition, a sample stage 112 on which a semiconductor substrate
111 that is a sample to be processed is placed is disposed at a
lower portion of the processing chamber 104 facing the shower plate
102. A radio frequency power source 114 which is a second radio
frequency power source is connected to the sample stage 112 via a
radio frequency matching unit 113.
By supplying a radio frequency power (second radio frequency power)
from the radio frequency power source 114 connected to the sample
stage 112, a negative voltage generally called a self-bias is
generated on the sample stage 112, and ions in the plasma are
accelerated by the self-bias and vertically incident on the
semiconductor substrate 111, so that the semiconductor substrate
111 is etched.
A control device 116 controls these devices described above based
on predetermined process conditions. In addition, the control
device 116 introduces the gas into the processing chamber 104 by
the method described below. The method includes: receiving data
related to plasma impedance from the microwave matching unit 108 or
the radio frequency matching unit 113, detecting whether the gas is
introduced into the processing chamber 104, and controlling a
timing that changes process parameters other than the gas after the
detection. Examples of such process parameter changes include a
change of the first radio frequency power between a first value
corresponding to a first step and a second value corresponding to a
second step, and a change of the second radio frequency power
between the first value corresponding to the first step and the
second value corresponding to the second step.
FIG. 2 illustrates that when the second radio frequency power is
changed in synchronization with the gas switching, how an applying
time t of the second radio frequency power fluctuates with respect
to a reference step time T according to a time period from a gas
supply setting (S10) until the gas is introduced into the
processing chamber 104 (S11).
In the following control, "a state where the gas supply setting
signal is on" means that the control device 116 outputs a gas
supply setting signal that instructs a gas supply to the gas supply
device 106, and "a state where the gas supply setting signal is
off" means that the control device 116 cuts off the output of the
gas supply setting signal to the gas supply device 106.
The gas supply setting signal transmitted from the control device
116 to the gas supply device 106 is changed between being turned on
and turned off, so as to be in synchronization with the reference
step time. Firstly, a gas flow rate, which is introduced into the
processing chamber 104 when the state where the gas supply setting
signal is on (S10) is set, increases later than the state where the
gas supply setting signal is on (S10) due to a delay in response to
the setting signal of the gas supply device 106, and a time
required for passing through the gas pipes 105 and the shower plate
102.
After it is detected that a desired gas is flowed into the
processing chamber 104 (S11), a radio frequency setting signal
transmitted to the radio frequency power source 114 is enabled to
be changed from Low to High (S12) in accordance with the
predetermined process conditions, and the second radio frequency
power is changed from the first value to the second value.
Accordingly, it is assumed that a time b is elapsed from the state
where the gas supply setting signal is on (S10) to a state where
the radio frequency setting signal is changed (S12). The time b is
set as a first time from a start time of the step to a start time
of the gas supply.
Further, in the state where the gas supply setting signal is off
(S13) after the time T is elapsed from the state where the gas
supply setting signal is on (S10), a delay in gas reduction occurs.
Specifically, the gas is discharged from an inside of the
processing chamber 104 later than the state where the gas supply
setting signal is off (S13) due to the delay in response to the
setting signal of the gas supply device 106 and a time required for
discharging the gas which is filled in the gas pipes 105 and the
shower plate 102.
After it is detected that the desired gas is discharged from the
inside of the processing chamber 104 (S14), the radio frequency
setting signal is enabled to be changed from High to Low (S15) in
accordance with the predetermined process conditions. Accordingly,
it is assumed that a time a is elapsed from the state where the gas
supply setting signal is off (S13) to a state where the radio
frequency setting signal is changed (S15). The time a is set as a
second time from a finish time of the step to a finish time of the
gas supply.
The time b from the state where the gas supply setting signal is on
(S10) to a state where the gas is introduced into the processing
chamber 104 and the time a from the state where the gas supply
setting signal is off (S13) to a state where the gas is discharged
from the processing chamber 104 vary depending on characteristics
such as the gas flow rate and gas viscosity of a target step and
characteristics such as the gas flow rate and gas viscosity of
steps before and after the target step. In addition, when gas
conditions are different in the steps before and after the target
step, the times a and b are not equal.
The radio frequency setting signal rises after the time b with
respect to a reference start time and then lasts for a time longer
than a reference finish time by the time a, so that a time t set
for the second radio frequency power of the target step becomes
(T+a-b), which is different from the reference step time by a time
difference (a-b).
The time difference (a-b) is a numerical value that varies
depending on responsiveness of the gas supply device 106, and the
time difference (a-b) varies depending on a machine difference in
the gas supply device of each plasma processing apparatus. As a
result, the time t=(T+a-b) during which the second radio frequency
power is applied also changes. Since the time during which the
second radio frequency power is applied greatly influences a result
of plasma processing performed on the semiconductor substrate, a
treatment result of the semiconductor substrate between the plasma
processing apparatuses varies depending on the machine difference
in the gas supply device.
In order to reduce the machine difference between the plasma
devices in the second radio frequency power applying time t
generated due to the machine difference in the gas supply device, a
time during which the gas of the target step flows in the
processing chamber 104 that determines the application time of the
second radio frequency power is necessary to be corrected by the
time difference (a-b) in order to counterbalance the fluctuation
caused by the time difference (a-b). In order to change the time
during which the gas flows, a gas supply time which is set as a
basis of the gas supply may be changed from T to {T-(a-b)}. By
setting the gas supply time to {T-(a-b)}, the applying time t of
the second radio frequency power becomes t=T-(a-b)+(a-b)=T and can
include no time difference (a-b), and becomes a time that does not
include the machine difference in the gas supply device, and the
like.
However, since the time a from the state where the gas supply
setting signal is off to the state where the target gas is
discharged from the processing chamber 104 can be known only after
the gas supply setting signal is actually off and the radio
frequency setting signal is changed, it is necessary to measure the
time a before adjustment. In a gas pulse method, since one cycle
including a plurality of steps is repeated a plurality of times,
the control device 116 may change the gas supply time of a target
cycle by using a time measured in an immediately preceding
cycle.
FIG. 3 is a flowchart in a case of controlling the gas supply
device 106 and the radio frequency matching unit 113 in the plasma
processing method by the gas pulse method in which the treatment
including two steps in the above method is repeated. FIG. 4 is a
timing chart when the gas supply device and the radio frequency
power source are controlled based on the flowchart.
At a start of the operations of the plasma processing apparatus
(SQ00 in FIG. 4), since a time from the state of the gas supply
setting signal is on until the gas is introduced into the
processing chamber 104 is not measured yet, in step S100 in FIG. 3,
the time a of the second gas introduction delay and the time b of
the first gas introduction delay are set to an initial value 0,
respectively.
In the gas pulse method, when a supply of one gas (first gas) is
stopped, a supply of the other gas (the second gas different from
the first gas) is started simultaneously. However, after the gas
supply setting is switched, if one gas filled in the gas pipe 105
is not pushed out by the other gas, the one gas is not discharged
and the other gas is not introduced. Therefore, it is assumed that
the time a of the second gas introduction delay is from a state
where the first gas supply setting signal is off (S13 in FIG. 2) to
a state where the first gas is discharged (S14 in FIG. 2).
Similarly, it is assumed that the time b of the first gas
introduction delay is from a state where the second gas supply
setting signal is off to a state where the second gas is
discharged.
Next, in step S101, the control device 116 transmits a first gas
supply setting signal to the gas supply device 106 so as to firstly
supply the first process gas (SQ01 in FIG. 4), and in step S102,
the control device 116 waits for awaiting time T.sub.0 until gas
flow and pressure in the processing chamber 104 are stabilized. The
first step is started from SQ02 in FIG. 4
In step S103, the control device 116 generates the plasma by the
electromagnetic wave generation power source 107 supplying a
microwave for plasma generation to the processing chamber while the
magnetic field generation coils 109 generating a magnetic field.
Further, the control device 116 supplies a radio frequency power
corresponding to a value of the second radio frequency power in the
first step to the sample stage 112 by the radio frequency power
source 114, and then, the etching treatment is started by
controlling each part of the device to a first process parameter,
such as generating the self-bias (SQ03 in FIG. 4).
In step S104, the control device 116 waits for a time obtained by
subtracting the time difference (a-b) from a first step time
T.sub.1 to be a reference, and then turns off a first process gas
supply setting signal in step S105 (SQ04 in FIG. 4), and meanwhile,
a second process gas supply setting signal is turned on (SQ05 in
FIG. 4). The first step finishes at SQ04 in FIG. 4, and the second
step starts at SQ05 in FIG. 4. Since a preceding cycle does not
exist at a first cycle, a=b=0, and a time for turning on the gas
supply setting signal remains T.sub.1, but after a second cycle,
the time for turning on the gas supply setting signal can be
changed by using the times a and b obtained in a previous
cycle.
After that, with the process proceeding from the first step to the
second step, the plasma impedance changes when the gas in the
processing chamber switches from the first process gas to the
second process gas, and therefore, a matching point of the second
radio frequency power also changes, and a reflected wave of the
second radio frequency power is generated (SQ06 in FIG. 4). In step
S106, the control device 116 detects that the gas in the processing
chamber 104 is switched from the first process gas to the second
process gas by using information of the reflected wave (SQ07 in
FIG. 4).
Next, in step S107, the control device 116 calculates a time
a.sub.0 from when the second process gas supply setting signal is
turned on (SQ05 in FIG. 4) to when the gas in the processing
chamber is switched to the second process gas (SQ07 in FIG. 4), and
in step S108, the second radio frequency power is set by the radio
frequency power source 114 (SQ08 in FIG. 4). In other words, the
control device 116 controls the radio frequency power source 114 so
as to change the value of the second radio frequency power in the
first step to the value of the second radio frequency power in the
second step. Here, the time from step S105 to step S106 is set to
a.sub.0 instead of a, that is because a is not updated until a next
cycle is proceeded. When proceeding to the next cycle, the control
device 116 substitutes a.sub.0 for time a to replace a (step S114
to be described later).
Since the introduction delay time and the discharge delay time of
the second process gas are opposite to those of the first process
gas, the control device 116 waits for a time obtained by
subtracting the time difference (b-a) from a second step time
T.sub.2 to be a reference in step S109. In other words, the control
device 116 controls a supply time of the second process gas, so
that the supply time of the second process gas becomes the time
obtained by subtracting the predetermined value (b-a) from the
second step time T.sub.2. Since step S109 is an end of one cycle
(SQ10 in FIG. 4), the control device 116 determines whether or not
the number of times set in step S110 is repeated, and when the set
number of times is not repeated, the control device 116 proceeds to
the next cycle.
Since the control device 116 supplies the second process gas for a
time {T.sub.2-(b-a)} in step S109, in step S111 which is the next
cycle, the second process gas supply setting signal is turned off
(SQ09 in FIG. 4), and meanwhile, the first process gas supply
setting signal is turned on (SQ11 in FIG. 4). When the gas in the
processing chamber 104 is switched from the second process gas to
the first process gas, a reflected wave of the second radio
frequency power is generated similarly as in step S106 (SQ12 in
FIG. 4), so that the control device 116 detects that the gas is
switched in step S112 based on this information.
Next, in step S113, a time b from when the first process gas supply
setting signal is turned on (S111 in FIG. 4) to when the gas in the
processing chamber 104 is switched to the first process gas (SQ13
in FIG. 4) is calculated.
As a result, since both the time a.sub.0 during which the first
process gas is switched to the second process gas and the time b
during which the second process gas is switched to the first
process gas are obtained, the control device 116 updates the time a
to a.sub.0 in step S114, and the flow returns to step S103 and
proceeds to the treatment of setting the second radio frequency
power to a value corresponding to the first step again for the next
cycle. At this time, the control device 116 controls a supply time
of the first process gas, so that the supply time of the first
process gas becomes the time obtained by subtracting the
predetermined value (b-a) from the first step time T.sub.1.
Thereafter, the etching treatment is continued in the gas pulse
method until it is determined in step S110 that a determined
treatment number of times is reached, and when it is determined
that the number is reached, the etching treatment is finished.
According to the present embodiment, as apparently illustrated in
FIG. 4, in the first cycle, the first step time T.sub.1 is
different from the time t.sub.1 for applying the second radio
frequency power according to the first step, and the second step
time T.sub.2 is different from the time t.sub.2 for applying the
second radio frequency power according to the second step. However,
by executing the above steps, T.sub.1.apprxeq.t.sub.1 and
T.sub.2.apprxeq.t.sub.2 can be achieved in the second and
subsequent cycles.
In other words, the control device 116 can control a supply time of
the first process gas by using the time a and the time b, so that
the supply time of the second radio frequency power in the first
step is substantially equal to the time of the first step, and can
control a supply time of the second process gas by using the time a
and the time b, so that the supply time of the second radio
frequency power in the second step is substantially equal to the
time of the second step.
The control device 116 controls the electromagnetic wave generation
power source 107 so as to change the value of the first radio
frequency power in the first step to the value of the first radio
frequency power in the second step. In this case, the control
device 116 can control a supply time of the first process gas by
using the time a and the time b, so that the supply time of the
first radio frequency power in the first step is substantially
equal to the time of the first step, and can control a supply time
of the second process gas by using the time a and the time b, so
that the supply time of the first radio frequency power in the
second step is substantially equal to the time of the second
step.
Since the time of gas introduction delay measured in the previous
cycle is used, it is impossible to completely equalize the applying
times t.sub.1, t.sub.2 of the second radio frequency power and the
step times T.sub.1, T.sub.2 to be the references. However, since
even the time of gas introduction delay in the previous cycle is a
time that includes the machine difference in the gas supply device,
it is possible to reduce the machine difference in the applying
time of the second radio frequency power between a plurality of
plasma processing apparatuses by changing a setting time of the gas
supply by using this time.
FIG. 3 and FIG. 4 are applied when the treatment is repeated with
one cycle including two steps, but the invention can also be
applied even when the number of steps constituting one cycle is
three or more.
There may be a case where a detection of an end point of the gas
switching is not executed in a part between the steps of the cycle
constituted by a plurality of steps. In order to apply the
invention even in that case, the gas delay time is calculated
between the steps of the detection of the end point of the gas
switching and changing the second radio frequency power, the gas
delay time between the steps of changing the second radio frequency
power without the detection of the end point is regarded as 0, and
the gas supply time may be adjusted.
In the present embodiment, the gas switching in the processing
chamber is detected based on the change in the plasma impedance,
and the time from when the gas supply setting signal is turned on
to when the gas is supplied to the processing chamber is
calculated. However, by a method for detecting gas switching in the
processing chamber using a change in emission spectrum intensity
from plasma in addition to this and a method in which a particle
measuring instrument is installed in the processing chamber to
detect gas switching by analyzing gas molecules in the processing
chamber, the time from when the gas supply setting signal is turned
on to the time when the gas is supplied to the processing chamber
can also be calculated.
The invention is not limited to the above embodiment, and includes
various modifications. For example, an inductively coupled plasma
(ICP) treatment device, a capacitively coupled plasma (CCP)
treatment device, and the like may be used, so that the invention
can be applied to switch the second radio frequency power after the
switching of gas in the processing chamber is detected.
Further, the embodiment described above have been described in
detail for easy understanding of the invention, and the invention
is not necessarily limited to those including all the
configurations described above, so various changes can be made
without departing from the scope of the invention.
REFERENCE SIGN LIST
101: Vacuum vessel 102: Shower plate 103: Dielectric window 104:
Processing chamber 105: Gas pipe 106: Gas supply device 107:
Electromagnetic wave generation power source 108: Microwave
matching unit 109: Magnetic field generation coil 110: Cavity
resonator 111: Semiconductor substrate 112: Sample stage 113: Radio
frequency matching unit 114: Radio frequency power source 115:
Vacuum exhaust port 116: Control device
* * * * *